fig1
From: Charge/orbital disordered states with smaller volume and higher entropy in transition-metal oxides
Figure 1. (A) Schematic phase diagram of NiS2 as functions of temperature T and pressure P. (B) Schematic phase diagram of Ca2RuO4. PI, AFI, PM, and AFM represent paramagnetic insulating, antiferromagnetic insulating, paramagnetic metallic, and antiferromagnetic metallic phases. (C) Energy per unit cell calculated by mean-filed approximation for the layered perovskite-type d-p model with d4 as a function of Jahn-Teller distortion (the ratio between the compressed/elongated apical Ru-O bond length and the in-plane Ru-O bond length. F and AF represent ferromagnetic and antiferromagnetic states. With the compression (elongation), the xy (yz or zx) orbitals are doubly occupied.
